Lithium in the sea water cannot be disregarded from the viewpoint of resources since the amount of sea water in inexhaustible although the content of lithium in the sea water is only about 0.17 PPM. However, it is disadvantageous to recover lithium directly from the sea water because of too much low concentration.
On the other hand, an industry of concentrating the sea water to obtain common salt and others has been already established. In the mother liquor from which the common salt and others have been separated out, that is brine, lithium must exist concentrated to be several tens times or more.